How can I connect a Hallberg-Rassy 12V socket to a USB-C charger for my iPhone?

Connect a plug that matches your Hallberg-Rassy's socket to a regulated 12V-to-USB-C charger; wiring the socket directly to USB-C will damage the phone. Identify the socket and check its voltage and polarity, then choose a ready-made adaptor or make a short adaptor lead.

Identify the socket

Hallberg-Rassy fittings vary with model, build year and previous owners' alterations, so the boat's name alone cannot identify the plug. Check the socket's shape, internal diameter and markings before ordering.

• Large round automotive socket: approximately 21mm internal diameter, accepting an ordinary cigarette-lighter USB-C car charger.
• Small round DIN/Hella socket: approximately 12mm internal diameter, often sold as a DIN ISO 4165, Hella, Merit or Powerlet fitting. An ordinary car charger will not fit directly.
• Two-hole or other older fitting: obtain the matching plug from a marine electrical supplier or ask HR Parts to identify it from a photograph and the boat's model and build number. Do not force a similar-looking plug into it.

Check the panel label too: some installations have separate 12V and 24V outlets. Set a multimeter to DC volts, confirm the voltage and identify positive and negative. Standard automotive and DIN sockets normally have positive at the centre contact and negative at the outer contact, but verify this on an older installation.

Choose a matching charger

For an automotive socket, buy a reputable 20W to 30W USB-C Power Delivery charger rated for the boat's supply voltage. Anker and Belkin are established charger brands. Budget roughly £15 to £35, depending on output and construction.

For a small DIN/Hella socket, use a USB-C PD charger with the correct DIN plug, or a short DIN-to-automotive-socket adaptor followed by the car charger. Budget roughly £10 to £20 for a basic adaptor lead, plus the charger. A direct-fitting charger has fewer connections; a short lead can keep a bulky charger clear of surrounding switches.

Look for an explicit USB-C PD specification, preferably including a 9V output profile. A USB-C-shaped outlet alone does not guarantee fast charging. A 20W unit provides useful iPhone fast charging; 30W gives some headroom. There is no need for a 65W unit solely for one phone.

Use a USB-C-to-USB-C cable for iPhone 15 and later models with a USB-C port. For an iPhone with a Lightning port, use an Apple or MFi-certified USB-C-to-Lightning cable.